Psoriasis is a common chronic inflammatory skin disease that may exhibit a variety of clinical manifestations. It is caused by cells in the top layer of the skin that divide more rapidly, and as a result, you get an impairment to the epidermal barrier function of the skin. There are many subtypes of psoriasis, and symptoms include thick, red, scaly plaques on the scalp, elbows, or in skin folds (like in the armpit, groin, or under the breasts). Pruritis (itching) is also a common symptom.